The marketing for freshly pressed and blended juices promises instant energy, weight loss, a flood of vitamins and minerals – all in a single, portable, gulpable serving.

Health-minded consumers seem to have bought the claims – and with them, gallons of juice.

Jamba Juice, which sells juices and smoothies, reported $55 million in revenue for the 13 weeks ending April 2. Beverage giant Coca-Cola tapped the juice trend early by acquiring Odwalla in 2001, and in 2007 PepsiCo followed suit with Naked Juice.

Tools for juicing at home are also a big business; one of the dozens of juicer choices, a stainless steel model with more than 100 Amazon.com reviews, sells for close to $1,200. Meanwhile, more than 40 books or e-books related to juice or smoothies have been released in the last 30 days alone on Amazon.com, with the majority mentioning health, weight loss or both in their titles.

But according to dietitians and nutrition scientists, juice is far from the healthiest way to consume fruit, and one expert went so far as to call its popularity a dangerous trend.

“The fruit juice industry has essentially taken the ‘apple-a-day’ mentality and used it to sell fruit juices as healthy,” said Barry Popkin, a professor in the department of nutrition at the UNC-Chapel Hill’s Gillings School of Public Health.

Popkin and other experts would rather see people eating whole fruit. Because most juicing methods remove the produce’s fiber, drinking juice omits one of the key benefits of eating fruit, while delivering huge amounts of sugar and calories.

“Every one of the long-term studies of the health effects of fruit juices shows that you increase your risk of diabetes and weight gain” with regular juice consumption, Popkin said.

One 2010 study in the American Journal of Epidemiology followed more than 43,000 adults in Singapore for five years and found that those who consumed two or more servings of fruit juice per week had a 29 percent higher risk of developing diabetes than those who didn’t drink juice regularly – not far behind the 42 percent increased risk for weekly soda drinkers.

Expensive, freshly pressed fruit juices from the local juice bar are no healthier than the kind sold in grocery stores, Popkin added.

Smoothies do provide fiber, as the entire fruit often goes into the blender, skins and all, but they still contain a lot of calories. Choosing a vegetable-based juice or smoothie is one way to reduce the sugar content, health advocates say.

However, epidemiological studies on juice consumption show correlations, not cause and effect, said Elizabeth Ward, a registered dietitian on Jamba Juice’s Healthy Living Council. Ward said she does not consider juices miraculous but, because of the vitamins and minerals, they are a good alternative to beverages that contain only calories.

Ward and Karen May, a spokeswoman for Naked Juice and Tropicana, agreed that most Americans don’t consume enough produce, and juice products are a good way to help fix that.

“Orange juice is a convenient and great-tasting way to help people meet nutrient needs, providing vitamin C, potassium and calcium … in fortified varieties,” May said.

But according to Lara Field, a pediatric dietitian at the University of Chicago Medical Center and founder of a nutrition counseling practice called Forming Early Eating Decisions, or FEED, the sugar in fruit juice far outweighs any possible benefit from the concentrated vitamins and minerals.

“Eating too much fruit can make us gain weight, just like eating too much candy,” Field said.

Plus, the fiber in fruit complements the vitamins and minerals, so juice drinkers miss out on the optimal health benefits, said Bethany Doerfler, clinical research dietitian in the division of gastroenterology at Northwestern Medicine.

Americans already are harming their health by not consuming enough fiber, said Joanne Slavin, professor in the Department of Food Science and Nutrition at the University of Minnesota and a self-described “fiber person.”

Diets higher in fiber are associated with lower risk of cardiovascular disease and lower body weight, Slavin said, yet most American adults only achieve half the recommended daily fiber intake, which is 25 to 38 grams.

Eating fiber also contributes to a feeling of fullness, or satiety, that helps prevent people from overeating. In one study, people who ate apple slices before lunch felt more full and subsequently consumed 15 percent fewer calories than those who drank apple juice.

Some nutrition experts acknowledge that drinking produce is better than consuming none at all.

“Considering the fact that more than 90 percent of Americans are not meeting their recommendations of daily fruit, 100 percent fruit juice is an easy and convenient way to meet these goals,” Diane Welland, a registered dietitian for the Juice Products Association, wrote via email.

Federal dietary guidelines state that 4 ounces of 100 percent fruit juice are equivalent to a half-cup of whole fresh fruit, Welland said.

Those guidelines also recommend that the majority of fruit consumed be whole fruit, but it can be challenging for adults to eat the suggested 1 1/2 to 2 cups of fruit and 2 1/2 to 3 cups of vegetables a day.

“Sitting down to a bowl of kale is intimidating,” said Doerfler, and that’s one possible reason juices and smoothies are so popular.